Pressure Limit in Volume Support Mode

Understanding Volume Support Mode

The American Thoracic Society recommends maintaining a plateau pressure ≤30 cmH₂O in volume support mode, with the ventilator automatically adjusting pressure support breath-by-breath to deliver the preset tidal volume while respecting this pressure ceiling 1, 2

The American College of Chest Physicians recommends setting the plateau pressure ceiling at ≤30 cmH₂O for patients with ARDS and acute respiratory failure, which represents the most widely validated pressure threshold associated with reduced mortality and ventilator-induced lung injury 1, 3, 4
For patients with normal lungs, consider a slightly lower threshold of ≤28 cmH₂O 2
In cases of increased chest wall elastance, plateau pressures up to 29-32 cmH₂O may be acceptable since the elevated pressure reflects chest wall stiffness rather than excessive lung stretch 2, 5

Set target tidal volume at 6 mL/kg predicted body weight as the starting point, with the ventilator adjusting pressure support to achieve this volume while respecting the pressure limit 1, 3, 4
Calculate predicted body weight using the formula: Male = 50 + 2.3 [height (inches) - 60]; Female = 45.5 + 2.3 [height (inches) - 60] [3, 4]
If plateau pressure exceeds 30 cmH₂O despite 6 mL/kg, reduce tidal volume target progressively down to 4 mL/kg predicted body weight 1, 3, 5

The American Academy of Sleep Medicine recommends that the maximum pressure support should not exceed 20 cmH₂O 6
For patients ≥12 years, maximum IPAP should be ≤30 cmH₂O; for patients <12 years, limit IPAP to ≤20 cmH₂O 6

Monitor plateau pressure to ensure it remains ≤30 cmH₂O 1, 2
Monitor driving pressure (plateau pressure minus PEEP) and intervene if values >15 cmH₂O are predicted to worsen outcomes 5

Increase pressure support by 1-2 cmH₂O increments every 5 minutes if tidal volume remains inadequate, but never exceed the 30 cmH₂O plateau pressure ceiling 6, 2
Patient effort generates higher transalveolar pressures for a given plateau pressure, so actively breathing patients may require more conservative pressure limits 1

No single ventilation mode has proven superior when lung-protective principles are maintained, but volume support offers theoretical advantages by automatically adjusting to changes in compliance and patient effort while maintaining pressure limits 1, 5